/***************************************************************************
 * ncat_lua.c -- ncat lua facilities                                       *
 ***********************IMPORTANT NMAP LICENSE TERMS************************
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 * Project"). Nmap is also a registered trademark of the Nmap Project.     *
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/* $Id: ncat_lua.c 38085 2020-10-05 23:00:30Z dmiller $ */

#include "ncat.h"
#include "ncat_lua.h"

static lua_State *L;
static int last_function_number;

static void report(char *prefix)
{
    const char *errormsg;
    errormsg = lua_tostring(L, -1);
    if (errormsg == NULL)
        errormsg = "(error object is not a string)";
    bye("%s: %s.", prefix, errormsg);
}

static int traceback (lua_State *LL)
{
    const char *msg;
    msg = lua_tostring(LL, 1);
    if (msg) {
        luaL_traceback(LL, LL, msg, 1);
    } else {
        if (!lua_isnoneornil(LL, 1)) {  /* is there an error object? */
            if (!luaL_callmeta(LL, 1, "__tostring"))  /* try its 'tostring' metamethod */
                lua_pushliteral(LL, "(no error message)");
        }
    }
    return 1;
}

void lua_setup(void)
{
    ncat_assert(o.cmdexec != NULL);

    L = luaL_newstate();
    luaL_openlibs(L);

    if (luaL_loadfile(L, o.cmdexec) != 0)
        report("Error loading the Lua script");

    /* install the traceback function */
    last_function_number = lua_gettop(L);
    lua_pushcfunction(L, traceback);
    lua_insert(L, last_function_number);
}

void lua_run(void)
{
    if (lua_pcall(L, 0, 0, last_function_number) != LUA_OK && !lua_isnil(L, -1)) {
        /* handle the error; the code below is taken from lua.c, Lua source code */
        lua_remove(L, last_function_number);
        report("Error running the Lua script");
    } else {
        if (o.debug)
            logdebug("%s returned successfully.\n", o.cmdexec);
        lua_close(L);
        exit(EXIT_SUCCESS);
    }
}
